Snap-action mechanism



' -1.618.963 l Feb. 22,1927. G. A. KNMK SNEP ACTION ECHANISM Filed Anvil 9.1919

Fw 1n zo 1% v @QM/MMM@ Patented Feb. 22, 1927.

PATENT OFFICE.

GEORGE KNAAX, OF MILWAUKEE, WISCONSIN.

SNAP-ACTION Application led April 9,

This invention relates to snap action mechanisms and the objectof the invention is to improve tleI cnstruction `of snap action mechanisms in the manner to be hereinafter described and claimed. I

Referring to the drawings which accompany this speciiication and form a part hereof, which drawings illustrate an embodiment of this invention, and on which drawings the same reference characters are used to designate the same arts wherever they may appear in each o the several views,\Fig. 1 is an elevation of a snap mechanism showing the parts in the relative positions which they occupy in one positive, predetermined position of the actuated member; F ig. 2 is an elevation of the same mechanism showing the parts in the 'relative' posit-ions which they occup in an impositive position of the actuate member when the parts are in positions for instantaneous change from one positive, predetermined position to another positive, predetermined position of the actuated member; and Fig. 3 is an elevation of the same mechanism showing the parts in the relative positions which they occupy when the actuated member has been snapped to another positive, predetermined posltion.

In all snap action mechanisms with which I am familiar, prior to my invention, there is a dwell in the operation of the mechanism `while parts are moving to change the actuated member from one positive, predetermined position to another positive, predetermined position. This dwell rendered the operation of the mechanism impositive and uncertain and was generally objectionable and in some mechanisms was positively injurious. The object of this invention is to eliminate the dwell or dwell point of such prior mechanisms. i

For ,the sake of simplicity of illustration and description I have illustrated this invention as' applied to a form of snap action, electric switch, and shall d cribe 1t as aplied to such use without, 1iowever, intending b'y such illustration and description to limit my invention to use with an electric switch.

Referrin to the drawings, the reference numeral 1 esignates a casin within which a bell-crank lever 2 is pivote upon a pivot MECHANISM.

1919. Serial No. 288,849.

5 and the spring 5 is adapted to swing the bell-crank lever 2 upon its pivot 3 in the opposite direction when the push ofthe plunger 4 decreases, in a manner which will be readily understood. It may be assumed that the plunger 4 is responsive to any changeable condition whatever, as for example, the pressure of a Huid or a temperature condition. Movements of sufficient magnitude of the bell-crank lever 2 will move the actuated member 6 from one positive, predetermined position to another positive, predetermined position. The actuated member 6 is pivoted upon a pivot 7 and has oppositely inclined faces 8 and 9 at one end which are shown by the drawings as meeting in a point 10. A pin 11 projects into an aperture 12 in the actuated member 6 and `serves as a stop to limit the extent of movement of the actuated member 6 about its pivot 7 in either direction. A spring-bridge switch'member 13 is illustrated as connected member 6 so as to be pressed against electric contacts 14 and 15 to establish an electric circuit betweenthe wires 16 and` `17 when the actuated member 6 is in one positive, predetermined position and so as to be removed from the electric contacts 14 and 15, to break the circuit, when the actuated member 6 is in another positive, predetermined position. i

A second bell-crank leve. 18 is pivoted to the bell-crank lever 2 by a pivot .19 and is illustrated by the drawings as composed of' aback 20 and sides-21 and 22. This construction is illustrated as a simple construction which may be adopted for convenience in manufacturing. An arm'23 is pivoted to the second bell-crank lever 18 and is provided with a part, which is illustrated as an anti-friction roller 24, adapted to bear against the end of the actuated member 6. A stop pin 25 is secured to the second bellcrank lever 18 and passes through an aperture 26 in the bell-crank lever 2 to`1imit the amplitude of movement of the second bellcrank lever 18 with res ct to the bell-crank lever 2. A spring 27 1s connected with the arm 23 and with the second bell-crank lever with the actuated tion with the switch memberl 13 pressedV against the contacts 14 and 15. lf now the plunger 4 is moved to the right, the bellcrank lever 2 is turned about its pivot 3 stretching the spring and the arm 23 is moved down, the antifriction roller 24 moving down the inclined face 8 and swinging the upper end of the arm 23 to the right and stretching the spring 27. `While this motion continues the actuated member 6 is held in a positive, redetermined position with the switch mem err13 pressed against the contacts 14 and15 because the right hand end of the actuated member 6 is being pressed down and, as the arm 23 is doing this pressing, the stop pin 25 will be in its uppermost position in the aperture 26. The instant the antifriction roller 24 runs onto the point 10 of the actuated member 6, the actuated member 6 is in an impositive position or condition and, if the movement of the plunger 4 were very slow as is frequently the case, the mechanism would not be under control.- The point 10 represents a position ofinaction, uncertainty or dwell in the positive action of the mechanism, but my invention eliminates the inaction, uncertainty or dwell of the prior mechanisms as will now be explained. When the antifriction roller 24 has rolled od the inclined face 8 onto the point 10, there is no resistance to the downward movement of the arm 23. rlhe tensionl of the spring 27 can, therefore, swing the second bell-crank lever 18 on its pivot 19 and pull thearm 23 down.. rlhe extent of movement is limited by the stop pin 25 in the aperture 26. The action is instantaneous no matter how slow may be the movement of the plunger 4 and the bell-crank lever 2. As soon as the antifriction roller 24 passes below the point 10, the tension of the spring 27 pulls the arm 23 to the left and the antifriction roller 24 presses against the inclined face 9 of the actuated member 6 and swings it about its pivot 7 into another positive, predetermined position in which the switch member 13 is removed from the contacts 14 and 15, as clearly shown by F ig. 3 of the drawings. When the spring 5 causes movement of the bell-crank lever 2 in the opposite direction, the mechanismincreases clined face, but this specific construction has been chosen for illustration because it clearly exemplifies the invention and its ad vantages.

What is claimed is:

1. The combination with a pivoted actuated member provided With oppositely inclined faces at one end, of a lever, means for moving the lever in opposite directions, an arm connected with said lever and provided with a part adapted to bear against the inclined faces at the end of the actuated member, a spring to press said arm against the actuated member, and means to move said arm independently with respect to said lever. l 2. rlhe combination with a pivoted actuated member rovided with oppositely inclined faces, of) a bell-crank lever, means to rock said lever in one direction, a spring to rock said lever in the opposite direction, a second bell-crank lever pivoted to the rst mentioned bell-crank lever, an arm pivoted to the second bell-crank lever and having a part adapted to bear against the inclined faces on the'actuated member, and a spring to actuate said arm andsaid second bellcrank lever.

3. r1he combination witha pivoted actuated member rovided with oppositely inclined faces, of) a lever, means to move said lever in one direction, a spring to move said lever in the opposite direction, a bell-crank lever pivoted to said lever and having a limited movement with respect thereto, an arm pivoted to said bell-crank lever and havin a part adapted to bear against the incline faces on the actuated member, and a spring connected with said arm and with said bellcrank lever to hold the arm in Contact with an inclined face on the actuated member.

4.' The combination with a pivoted actuated member provided with oppositiely inclined faces at one end, of a lever, means for moving the lever in opposite directions, an arm connected with said lever and provided with a part adapted to bear against the inclined faces at the end ofthe actuated member, a spring for normally holding said arm and actuated member in contact, and means to move said arm independently with respect to said lever.

5. rilhe combination with a pivoted actuated member provided with oppositely inclined faces at one end, of a lever, means for .moving the lever in o posite directions, an arm connected with said lever and provided with a part adapted to bear against the inclined faces at the end of the actuated member, a spring for normally holding said arm and actuated member in Contact and said lever having an aperture therein, said arm having a part passing loosely through said aperture to provide for limited movement of the arm independently Y`of and relative to said lever.

`6. The combination with a pivoted actuber, a spring for :normally holding said arm f ated member provided with oppositely 1nand actuated member in contact, and a lostclnedpfaees atene/end, of a lever, means for motion connection between said arm and 10 movlng the lever in oppos1te-drect1ons,- an lever.-

arm connected with said lever and provided In witness whereof I hereto aix my signa- Y with a. part adapted to bear against the in 'tur-e. p

clined faces at the end of, the actuated mem- .GEORGE A. KNAAK. 

